Conveyer operated screening device



Feb. 9, 1932 H. A. DAVIS 1,844,383

CONVEYER OPERATED SCREENING DEVICE Filed May 17, 1929 Sheets-Sheet l INVENTOR V/A/A ATTORNE MMQM.,

Feb. 9, 1932.. H. A. DAVIS GONVEYER OPERATED SCREENING DEVICE Filed May 17, 1929 2 Sheets-Sheet 2 www@ ,fw/f M ATTORNEY Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE HAROLD A. DAVIS, OF CHICAGO, ILLINOIS, .ASSIGNOR T GENERAL CHEMICAL COM- IANY, OI TEW YRK, N. Y., .A CORPORATION 0F NEW` YORK CONVEYER OPER-ATED SCREENING DEVICE Application led May 17, 1929.

This invention is concerned with apparatus for conveying and separating;` mixtures oi solid constituents which are in different degrees of lineness or subdivision. Its

chief object is to provide an automatic screening' apparatus for sifting out the smaller particles troni admiiitnrc in a continuously movingr stream consisting oi, these and larger particles, such as 'the output mixture 'from a suit culte furnace, a pulp drier, or the like.

Another object ot' the invention is to provide conveying and sepaitutingapparatus ot such nature that no driving or operating; .mechanism other than that provided by the 16 conveyor itself is required to operate the separator.

A particular object of the invention is to provide a screening device which will have hut a i'ew parts ot an extremely simple, in

20 expensive cons ruction, and which will be unlikely to become clogged or `jammed with the material or otherwise get out of order.

The preferred embodiment oit Athe inventive idea is shown in the accompanying d ,'awings, wherein llig. 1 is a perspectiiife view ot the apparatus;

Fig. 2 is a longitudinal section thereof on line 12-:2 ot Fig'. 1; and

Fig. is a plan view of the apparatus. Referring now to the structure illustrated, the apparat-usf: comprises a chute made up in the usual manner into a hollow, more or less rectangular trough 1 having' as desired an open or a closed top, and a bottom 1 closed except at the place where the separation and delivery of one ot the constituents ot the mixture is desired. lt this place there is a rectangular opening' 2 in the bottom ot the trough, and extending` transversely across the center of' this opening` a shaft 3 is journulcd freely in straps et attached to the bot-- tom dal s on the side-girders ot' the trough.

The screen 5, preferably inv the form et a "t5 perforated plate-ot sheet metal, is mounted in the opening` on shalt't 3, the shaft supporting the screen substantially on its transverse median line.

The screen is tree to roel; or oscillate about il the shaitt as a pivot from one side to the other.

Serial No. 363,917.

rlo limit the extent oi the upward and down Yard movement of the ends ot the screen, transversely extending stops G are provided at each end of the openinl below the bottom .level of the trough, and are connected thereto by suitable angle irons or the like 7.

The plate constituting screen 5 is perforated with oval holes 9, the axes ot the ovals pref erably being; parallel to each other and to the direction of movement of the material. These ovals are et the proper size and shape to permit the passage et relatively fine material, but Anot large enough to let the larger pieces or cakes `i'all through or hinder their passage over the screen.

0n the longitudinal center-line of the plate, situated at equal distances from the transverse center-line of the shaft, are two lugs or cams 10, preferably of rectangular shape as shown in Fig. 3, and both chamfered or rounded oil on their forward edges 11, as shown. These lugs are welded or` otherwise firmly attached to the plate.

An endless conveyer 12 moves over the bottom et the trough for the purpose ot pushing or dragging the mixture of solid materials along' the same. The conveyer shown consists et a pair of chains 13 having` heavy bars or pushers 14; mounted between them at suitable intervals. The pushers 14 engage the lugs or cams 10 on the screen which causes the screen to be roch-ed or oscillated `about the shaft 3 on which it is mounted.

Byinaking the longitudinal spacing` ot the lugs 10 only slightly smaller than the spacingl or pitch of the pushers 14, the second or rear lng); 10 is engaged hy one ot the pushers ll very quickly after the forward lug 10 has been engaged by the preceding pusher 14. In this way a relatively rapid rocking' or 'vibration of the screen produced.

lt will be understood that the rapid vibration of the scr-een produced in the manner just .described causes the Einer particles of the solid material movingI over the screen to pass through the intel-sticos or perfo-rations into the hopper or bin 15. The coarser particles which are too large to pass through the screen move on aloner the trough under the action of the conveyor, and are carried to a point of further treatment or to storage, as desired.

The perforated plate comprising the screen 5 is bent downwardly at each end as indicated at 8 of Fig. 2 to form feet to engage the stops 6 and to facilitate the movement of the material in the trough or chute on to and olf of the screen. Moreover, it willbe noted that the outer ends of the feet 8 are close to the inner walls of the angles 7 so as toleave just enough clearance to permitthe plate to vi-` brate freely. Thus it is impossible for large particles of the solid material passing over the screen to become lodged in this space and cause jamming of the screen. Y The movement of each end of the screen away Vfrom the stops 6 is howeversufficient to permit any relatively line material which may have entered the space at the ends of the screen to pass horizontally :over the stops 6 and mix with the material which has passed through the screen. v

The elevation of shaft 3 upon which the screen is supported is preferably such as to bring the top of the screen slightly below the upper surface of the bottom of the trough when the screen is in mid-position. Also the clearance between the bottoms ofthe feet 8 and the stops 6 is such as to cause the upper surfaces of the ends of the screen to be raised slightly above the bottom of the .trough when the opposite end of the screen `is in engagement with one of the stops 6. This facilitates the passage of the coarse material off from the rear end of the screen on to the bottom of the trough because during a part of the cycle of vibration the rear end of the screen is raised vabove the bottom of the trough.V This, moreover, enables the solids to pass on to the front 'end of the'screen without difficulty because having spaced elements preferably extending transversely of the trough to engage the lugs l0 might be used. Also in the conveyer shown the pusher bars 14 are mounted with the bars at right angles to the chain but while this construction is preferable, it is not neces- -sary as far as the operation of the vibrating screen is concerned and the bars could be otherwise mounted as, for example, at a diagonal to the chain. y

VIn operation my improved screening device is extremely satisfactory because of freedom from clogging, and because of the effectiveness with which the ne material is separated from the coarser material. The rapid vibration imparted to the screen shakes the finer particles free from the coarser ones and the lines pass down through the perforations of the screen without difiiculty. Moreover the screen operates in such a way that the material passes over it without increasing the drag on the conveyer to any great extent. The particular mounting of the screen and construction of the ends of the screen prevent the coarse material from becoming jammed between the stationary and moving parts in such a way as to prevent the vibration of the screen. A j

An important advantage of the improved screening device is that it can be installed Vwithout difficulty Aat any convenient point in the conveyer inasmuch as it requires for its operation no separate drive mechanism. All that isV necessary is to make an opening at the desired' point in the conveyer trough, surroundit with suitable steel shapes to protect the edges of the trough and to form the stationary parts and mounting for the screen.

A vfurther advantage ofthe screening device is its low cost of manufacture and installation which proceeds from its simplicity and small number of parts. y

It will be understood that the foregoing description of the preferred embodiments of my invention is to be considered as an exeniplifying disclosure and that the invention extends to other embodiments which are included within the terms of the appended claims. Y

-IclairnvV 1. A conveyer system comprisinga conveyer, a conveyer chute therefor having an opening in the bottom thereof, a screen pivotally mounted in said opening, and co-actlng means on the conveyer and on the screen for oscillating said screen by the passage of .the conveyer thereover. i

2. In a conveyer system including a coni veyer and a trough therefor having an opening therein, a screening device for separating constituents of the material conveyed comprising a shaft extending transversely of said opening and supported at the` sides thereof, aiscreen mounted thereon for permitting only the finer particles of the material to fall through said opening, actuating means associated with the screen, and means on said conveyer for engaging said actuating means during the travel of the conveyer and causing the rocking Vof the screen about its supporting shaft. f

3. Ina conveyer system including a conveyer and a. trough therefor having an opening therein, a screen, means for'supporting y the screen substantially at its transverse me- -dian line in the opening in the trough, a

transverse stop member at each end of the opening for limiting the verticalmovement of each Vend of the screen, the screen having downwardly curved ends terminating in feet for engaging the stop members, means for causing the screen to vibrate vertically on its pivotal support, and vertical walls at each Aeo lSO

end of the opening in the trough connecting the upper surface of the bottom of the trough with the tra-neve se stop members, and located in close proximity to the downwardly curved ends of the screen so as to prevent the passage of large particles of material, but 'freely passing relatively small particles Without causing jamming of the screen.

ln a conveyor system including a conveyer and a trough therefor having` an open-l ing therein, a screen mounted in said opening on centrally located pivots to permit vibration of the screen, means for causing the screen to rib nte, and stops for limiting the vertical movement of each end of the screen positioned to permit each end of the screen to rise above the bottom surface of the trough during a portion of the cycle of vibration.

In a conveyor' system including` a. con vcyer and a trough therefor hai/'ing an opening therein, a screen mounted in said opening on centrally located pivots to permit vibration of the screen, means for causing the screen to vibrate, said pivots being disposed so as to support the upper surface of the screen at an elevation slightly below the upper surface of the trough when the screen is in the mid-position of its cycle of vibration, and stops at each end of the screen positioned to permit each end of the screen to rise slightly above the bottom surface of the trough during a. portion of the cycle of vibration.

t3. In a conveyor' system including a conveyor and a trough therefor havingl an opening' therein, screen mounted in said opening' on centrally located pivots to permit vibration of the screen, means for causing the screen to vibrate, stops for limiting` the vertical movement of each end of the screen positioned to pern'iit only a limited amplitude of vibration and to permit ach end of the screen to rise above the bottom surface of the trough during1 a portion of the cycle of 'vila-ation, and the screen being provided with dmvnvvardly curved end portions, said limited viln'ation and said curved end portions serving to facilitate the reception and discharge of solid material from respectively the front and rear ends of the screen.

'l'. In a conveyor system including a conveyor and a trough therefor having an opening' therein, a screen pivotally mounted in the open ing for vertical vibration about its transverse median line, a pair of lugs projecting upwardly from the screen, one of said lugs being on each side of the transverse center line of the screen, said lugs being substantially equi-distant from said center line, and the conveyor having spaced transverse bars adapted to engage said lugs during the travel of the conveyor and cause the vibration of the screen.

8. In a conveyor system including a conveyer and a trough therefor having an opening therein, a screen pivotally mounted in the opening for vertical vibration about its transverse median lino, a pair of lugs projecting upwardly from the screen one on eac-h sido of the transverse median line thereof, said lugs being substantially equi-distant from said median line, the conveyor havingl spaced transverse bars adapted to engage said lugs during the travel of tho conveyor and causo the vibration of the screen, the spacing of said lugs being such that the first lug is ongaged by a transverse bar of the conveyor to depress the front portion of the screen and thereafter the second of said lugs is engaged by the preceding transverse bar to depress the rear portion of the screen.

9. In combination, a conveyor, a screen mounted beneath the conveyor, and means on the conveyor coactingr with means on the screen for moving the screen on movement of the conveyor.

10. In combination, a conveyor, a vertically oscillatable screen mounted beneath the conveyor, and means on the conveyor coacting With means on the screen for oscillating the screen on movement of the conveyor.

1l. In combination, a conveyor', a screen mounted beneath the conveyor', screen actuating means on the conveyor, a member positioned to engage the actuating means and connected to the screen for moving the screen on movement of the conveyor.

12. In combination, a conveyor, a vertically oscillatablo screen mounted beneath the conveyor, screen actuating means on the conveyor, a member positioned to engage the actuating moans and connected to the screen for oscillating the screen on movement of the conveyor.

13. In a conveyor system including a conveyor and a trough having an opening therein, a screen mounted in the opening, screen actuating means on the conveyor, a member positioned to engage the actuating means and connected to tho screen for moving the screen on movement of the conveyor.

14. In a conveyor system including a conveycr and a trough having an opening therein, a vertically oscillatable screen mounted in the opening, screen actuating means on the conveyor, a member positioned to engage the actuating means and connected to the screen for oscillating the screen on movemont of the conveyor.

In testimony whereof, I aitiX my signature.

HAROLD A. DAVIS. 

